China has vowed to intensify controls on social media and instant messaging tools, in the highest-level official response to the extraordinary surge in microblogging in the country.

The communique from the Communist party central committee follows growing boldness among users, who have discussed sensitive topics, highlighted scandals and attacked official abuses or inefficiency.

This summer’s high-speed rail crash in Wenzhou led to an outpouring of fury on microblogs about the handling of the disaster. That spilled over into mainstream media.

China already has the most extensive and sophisticated internet control system in the world. But censors have struggled to keep up with the flow of information on popular microblogs. The number of registered users on domestic services reached 195 million by the end of June, triple the figure of six months earlier, according to the China Internet Network Information Centre.